Universe Today

January 30, 2008December 26, 2015 by Nancy Atkinson

A Young Star Grows Up

Remember when you were young and how Mom always told you to eat everything on your plate so you would get big? Well, there’s a young star heeding that advice about 2,600 light years from Earth in the constellation Monoceros. Known as MWC 147, this young stellar object is devouring everything on its “plate,” the disk of gas and dust that surrounds it. Astronomers are witnessing how this star is gaining mass, and is on its way to becoming an adult.

Using the Very Large Telescope Interferometer, ESO (European Organization for Astronomical Research in the Southern Hemisphere) astronomers have peered into the disc of material surrounding MWC 147, witnessing how the star gains its mass as it matures. This star is increasing in mass at a rate of seven millionths of a solar mass per year. Ah, these young stars. It seems like they grow up so fast these days.

MWC 147 is less than half a million years old. If our 4.6 billion year old Sun is considered to be middle-aged, MWC 147 would be a 1-day-old baby. This star is in the family of Herbig Ae/Be objects. These are stars that have a few times the mass of our Sun and are still forming, increasing in mass by swallowing material present in a surrounding disc.

Being 6.6 times more massive than the Sun, however, MWC 147 will only live for about 35 million years, or to draw again the comparison with a person, about 100 days, instead of the 80 year equivalent of our Sun.

We’re still learning about the morphology of the inner environment of these young stars, and everything we can discover helps us to better understand how stars and their surrounding planets form.

The observations by the ESO astronomers show that the temperature changes in this area are much steeper than predicted by current models, indicating that most of the near-infrared emission emerges from hot material located very close to the star, within one or two times the Earth-Sun distance (1-2 AU). This also implies that dust cannot exist so close to the star, since the strong energy radiated by the star heats up and ultimately destroys the dust grains.

“We have performed detailed numerical simulations to understand these observations and reached the conclusion that we observe not only the outer dust disc, but also measure strong emission from a hot inner gaseous disc. This suggests that the disc is not a passive one, simply reprocessing the light from the star,” explained astronomer Stefan Kraus. “Instead, the disc is active, and we see the material, which is just transported from the outer disc parts towards the forming star.”

Also of note is the beautiful image of the region surrounding MWC 147, which I’ll post below. The number of stars in this image is incredible, and is reminiscent of the â€œgrains of sandâ€? comment by Carl Sagan. This is a wide field image taken by Stephane Guisard of ESO with a 200 mm lens.

Original News Source: ESO Press Release

January 29, 2008December 26, 2015 by Tammy Plotner

Venus and Jupiter Dazzle the Eye on February 1

Although no one likes getting up early, the morning of February 1 will be worth the effort. Just before local dawn, the scene is set as brilliant planets Venus and Jupiter rise together ahead of sunrise. The planetary pair will be so close together they can easily fit in the same binocular field of view and in a low power, wide field telescope eyepiece. Even if you don’t use optical aid, the dazzling duet will capture the eye….

“Your eye is like a digital camera,” explains Dr. Stuart Hiroyasu, O.D., of Bishop, California. “There’s a lens in front to focus the light, and a photo-array behind the lens to capture the image. The photo-array in your eye is called the retina. It’s made of rods and cones, the fleshy organic equivalent of electronic pixels.” Near the center of the retina lies the fovea, a patch of tissue 1.5 millimeters wide where cones are extra-densely packed. “Whatever you see with the fovea, you see in high-definition,” he says. The fovea is critical to reading, driving, watching television. The fovea has the brain’s attention. The field of view of the fovea is only about five degrees wide. On Friday morning, Venus and Jupiter will fit together inside that narrow angle, signaling to the brain, “this is worth watching!”

But Venus and Jupiter aren’t the only pair sparkling the pre-dawn skies. If you look a bit further south, you’ll notice that the waning Moon and Antares are also making a spectacular show! While they will be separated by a little more distance, the red giant and earthshine Moon will still fit within the eye’s fovea – and a binocular field of view!

Where will all the celestial action take place? Look no further than the ecliptic plane – the imaginary path the Sun, Moon and planets take across the sky. For many observers, the ecliptic plane begins low in the southeast – but southern hemisphere viewers have a much different view! But don’t wait until Friday to have a look. If you’re up before dawn, step outside and watch as Venus and Jupiter draw closer together over the next several days and the Moon creeps to the east. On February 3, the Moon will form a line-up with the two planets and a striking triangle on the morning of February 4. Be sure to have a camera on hand and share your photos!

Wishing you clear skies….

January 29, 2008December 26, 2015 by Nancy Atkinson

Method to Test String Theory Proposed

Image of 10 dimensional super strings. Credit: PBS.

What is the universe made of? While general relativity does a good job providing insights into the Big Bang and the evolution of stars, galaxies and black holes, the theory doesn’t help much when it gets down to the small stuff. There are several theories about the basic, fundamental building blocks of all that exists. Some quantum physicists propose string theory as a theory of “everything,” that at the elemental heart of all matter lie tiny one-dimensional filaments called strings. Unfortunately, however, according to the theory, strings should be about a millionth of a billionth of a billionth of a billionth of a centimeter in length. Strings are way too small to see with current particle physics technology, so string theorists will have to come up with more clever methods to test the theory than just looking for the strings.

Well, one cosmologist has an idea. And it’s a really big idea.

Benjamin Wandelt, a professor of physics and astronomy at the University of Illinois says that ancient light from the beginnings of our universe was absorbed by neutral hydrogen atoms. By studying these atoms, certain predictions of string theory could be tested. Making the measurements, however, would require a gigantic array of radio telescopes to be built on Earth, in space or on the moon. And it would be really gigantic: Wandelt proposes an array of radio telescopes with a collective area of more than 1,000 square kilometers. Such an array could be built using current technology, Wandelt said, but would be prohibitively expensive.

So for now, both string theory and this method of testing are purely hypothetical.

According to Wandelt, what this huge array would be looking for are absorption features in the 21-centimeter spectrum of neutral hydrogen atoms.

“High-redshift, 21-centimeter observations provide a rare observational window in which to test string theory, constrain its parameters and show whether or not it makes sense to embed a type of inflation — called brane inflation– into string theory,” said Wandelt. “If we embed brane inflation into string theory, a network of cosmic strings is predicted to form. We can test this prediction by looking for the impact this cosmic string network would have on the density of neutral hydrogen in the universe.”

About 400,000 years after the Big Bang, the universe consisted of a thick shell of neutral hydrogen atoms (each composed of a single proton orbited by a single electron) illuminated by what became known as the cosmic microwave background.

Because neutral hydrogen atoms readily absorb electromagnetic radiation with a wavelength of 21 centimeters, the cosmic microwave background carries a signature of density perturbations in the hydrogen shell, which should be observable today, Wandelt said.

Cosmic strings are filaments of infinite length. Wandelt compared their composition to the boundaries of ice crystals in frozen water.

When water in a bowl begins to freeze, ice crystals will grow at different points in the bowl, with random orientations. When the ice crystals meet, they usually will not be aligned to one another. The boundary between two such misaligned crystals is called a discontinuity or a defect.

Cosmic strings are defects in space. String theory predicts that a network of strings were produced in the early universe, but this has not been detected so far. Cosmic strings produce fluctuations in the gas density through which they move, a signature of which Wandelt says will be imprinted on the 21-centimeter radiation.

Like the cosmic microwave background, the cosmological 21-centimeter radiation has been stretched as the universe has expanded. Today, this relic radiation has a wavelength closer to 21 meters, putting it in the long-wavelength radio portion of the electromagnetic spectrum.

If such an enormous array were eventually constructed, measurements of perturbations in the density of neutral hydrogen atoms could also reveal the value of string tension, a fundamental parameter in string theory, Wandelt said. “And that would tell us about the energy scale at which quantum gravity begins to become important.”

But questions remain about the validity of this experiment. Also, could the array somehow be “shrunk” to search only a small area of the 21-centimeter radiation? Or possibily, could an instrument similar to WMAP (Wilkinson Microwave Anisotropy Probe) be constructed to look at the entire sky for this radiation?

Wandelt and graduate student Rishi Khatri describe their proposed test in a paper accepted for publication in the journal Physical Review Letters, and the paper is not yet available for public review.

Original News Source: University of Illinois Press Release

January 29, 2008December 26, 2015 by Nancy Atkinson

Tricky January 30 Spacewalk to Repair ISS Solar Array

Space station astronauts will conduct a spacewalk on January 30 to replace a faulty positioning motor at base of the station’s two starboard solar arrays. ISS Expedition 16 commander Peggy Whitson and flight engineer Dan Tani will change out the motor in hopes of regaining more power-generating ability of the orbiting laboratory’s expansive solar wings. But the astronauts will have to work fast, since they can only work on the electricity-producing arrays when the sun isn’t shining on them. That only allows 33 minute increments of time to conduct the repairs.

Because of the faulty motor, the solar arrays have been unable to track the sun continuously since early December, when the joint motor suffered a series of electrical shorts. In an earlier spacewalk, Tani and Whitson surveyed the damage and ruled out meteorite damage to the motor. Without the repair, the space station would have enough power to make it through at least the next shuttle mission, currently scheduled for a Feb. 7 launch, but not much further said Kirk Shireman, NASA’s ISS deputy program manager.

If the Wednesday spacewalk is successful, the ISS will have power to last through the planned arrival of a massive Japanese laboratory in April and into the summer, Shireman added.

The broken motor controls a beta gimbal joint that pivots one of the station’s two starboard solar wings to face the sun. NASA hopes replacing the whole motor, a garbage-can sized device that weighs about 250 pounds (113 kilograms), with a backup will fix the problem. The replacement motor was already on board the station, brought up on an earlier flight.

For safety reasons, the astronauts can only work while orbiting on the night side of Earth. If the sun was shining on the solar panels while Whitson and Tani were working on the joint, they would be at risk of shocks due to the high power levels surging through the arrays. They will only have about 33 minutes of total â€œshadeâ€? at a time to conduct their work. If they can’t replace the motor during one night side pass, they’ll have to wait and finish their task on the next pass. The station continuously orbits the Earth every 90 minutes.

NASA officials said the repair is possible to do in one 33 minute segment, but only if everything goes as planned. Since the damage only occurred recently, Whitson and Tani have not rehearsed the spacewalk in the Neutral Buoyancy Lab in Houston, a giant swimming pool where astronauts train for spacewalks. However, other astronauts on the ground have rehearsed the repair and shared their insights with the astronauts on board the ISS.

Wednesday’s EVA will be the sixth career spacewalk for both Whitson and Tani, and the fifth for the station’s Expedition 16 crew.

This spacewalk is unrelated to on-going analysis of problems with a massive Solar Alpha Rotary joint on the right side of the station’s main power truss that is needed to turn outboard arrays to track the sun. Astronauts discovered metal shavings in the gear’s attached metal ring during past spacewalks, and engineers do not yet understand the cause of the unusual erosion. Whitson and Tani will take another look at the 10-foot (3-meter) wide gear if they have extra time during Wednesday’s excursion, mission managers said.

NASA will broadcast the Expedition 16 crew’s fifth spacewalk live on NASA TV beginning at 4:00 a.m. EST (0900 GMT) on Jan. 30.

Original News Source: NASA TV, Space.com

January 29, 2008December 26, 2015 by Nancy Atkinson

Are We Living in a New Geologic Epoch?

Have humans changed our planet Earth so much in the past 200 years that we are now living in a new geological age? A group of geologists believes this is the case. They have formally proposed designating a new geologic epoch, the Anthropocene, which would encompass the past 200 years or so of geologic history. The action is appropriate, they say, because during the past 2 centuries, human activity has caused most of the major changes in Earth’s topography and climate.

Like rings in a tree, each layer in Earth’s geologic record reflects the conditions of the time it was deposited and offers a glimpse into Earth’s past. In this geologic history that is written in the rocks and soil of our planet, researchers have differentiated the layers into classifications of time called eons, eras, periods, epochs, and ages that reflect characteristic conditions. For example, the Carboniferous period, which lasted from 360 million to 300 million years ago, is known for the vast deposits of coal that formed from jungles and swamps. Even some of the longer stretches have been named based on biology, such as the Paleozoic (“old life”) and the Cenozoic (“recent life”).

Earth has been has always been subject to the same kinds of physical forces–wind, waves, sunlight–throughout the planet’s existence. But the life that has arisen on the planet has had a much more varied impact such as the rise of plants that has shaped the planet in dramatic ways. But in the past 200 years, ever since the human population has reached 1 billion, our influences have affected the composition of Earth’s strata, altering the physical and chemical nature of ocean sediments, ice cores and surface deposits. Some of these influences are the use of fossil fuels and the growth of large cities.

British Geologist Jan Zalasiewicz and several colleagues argue that the International Commission on Stratigraphy should officially mark the end of the current epoch. That would be the Holocene (“entirely recent”), which started after the end of the last ice age, about 10,000 years ago. The new epoch would be the Anthropocene.

The evidence the geologists cite include the dramatic increase in lead concentration in the soil and water since about 1800 and the increase of carbon dioxide in the atmosphere. They claim that human processes now vastly outpace the equivalent natural forces. “A reasonable case can be made for the Anthropocene as a valid formal unit,” Zalasiewicz says.

The argument has merit, says American geologist Richard Alley. “In land, water, air, ice, and ecosystems, the human impact is clear, large, and growing,” he says. “A geologist from the far distant future almost surely would draw a new line, and begin using a new name, where and when our impacts show up.”

Original News Source: AAAS ScienceNow

January 28, 2008January 24, 2021 by Fraser Cain

Alarmist Asteroid 2007 TU24 Video

At the time I’m writing this, asteroid 2007 TU24 has nearly passed the Earth. As we’ve been hammering on here on Universe Today, the Earth is completely safe. Only if you have a telescope and know exactly where to look, will you stand a chance of spotting the flyby.

Even though he posted a video last week, debunking the collision claims, Bad Astronomer and (former) friend Phil Plait seems to have recanted.

Lowest form of life? Ouch.

Thanks to IronmanAustralia for the laugh. I’m still wiping the tears out of my eyes.

On another note, this is the first time I’ve tried embedding a YouTube video in Universe Today. I’m sure I’ve messed it up somehow. Let me know if you like this, and want more.

January 28, 2008December 26, 2015 by Fraser Cain

Are the Martian Winds Still Resurfacing the Planet?

The Martian atmosphere is tenuously thin; just 1% as thick as the Earth’s. And yet, it boasts a surprising array of weather systems, including clouds and global dust storms. The winds push dunes across the Martian surface and towering dust devils carve crisscrossed trails across the desolate landscape.

Here on Earth, wind, water and the slow movement of tectonic plates reshape the surface of our planet. On Mars, though, there’s not a drop of liquid water to be seen, and the planet’s plates seized up eons ago.

Only wind remains to rework the surface of the planet. But scientists wonder if the features we see on Mars today were formed recently by the blowing winds, or were created eons ago, when the winds and air pressure were much stronger.

Recent images from NASA’s Mars Reconnaissance Orbiter show various regions of Mars pushed around by winds.

“We’re seeing what look like smaller sand bedforms on the tops of larger dunes, and, when we zoom in more, a third set of bedforms topping those,” said HiRISE co-investigator Nathan Bridges of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “On Earth, small bedforms can form and change on time scales as short as a day.”

With the high-resolution HiRISE camera on MRO, scientists are able to see details for the first time. The images show sediments deposited on the downwind side of rocks. These windtails show where the most current winds have blown. When the winds change directions, the old windtails are obscured, and new ones are formed behind the rocks. This technique allows researchers to map wind directions across the entire planet.

Scientists have also discovered wind-scoured ridges called “yardangs”. The HiRISE images show their surface texture and fine-scale features to help explain how they form.

“HiRISE is showing us just how interesting layers in yardangs are,” Bridges said. “For example, we see one layer that appears to have rocks in it. You can actually see rocks in the layer, and if you look downslope, you can see rocks that we think have eroded out from that rocky layer above.”

And in the image attached with this story, you can see the paths taken by dust devils as they pass across the surface of Mars.

Original Source: NASA/HiRISE News Release

January 28, 2008December 26, 2015 by Fraser Cain

Stars Form Better in the Cosmic Suburbs

Galaxies, like people, tend to stick together. These galaxies collect together into communities large and small, called clusters and even superclusters. According to new research gathered by NASA’s Spitzer Space Telescope, stars seem to form better in the cosmic suburbs of these clusters.

Galaxy clusters can be enormous, locking together thousands of galaxies into a mutual gravitational dance. Seen from afar, these groups of galaxies form large blobs (the clusters) linked together by spider web-like filaments that stretch for millions of light-years. The filaments contain the smaller collections of galaxies working their way towards the largest clusters.

Spitzer’s infrared view revealed two of these filaments in the galaxy cluster Abell 1763. Galaxies are traveling along these filaments, and will eventually collide with the larger cluster itself.

The researchers used Spitzer to measure the rates of star formation in both filaments and the larger galaxy cluster itself. They found that the filaments have much higher rates of star formation than the cluster.

“This is the first time we’ve ever seen a filament leading into a cluster with an infrared telescope,” says Dario Fadda, of the Herschel Science Center, which is located at the California Institute of Technology in Pasadena, California. “Our observations show that the fraction of starburst galaxies in the filaments is more than double the number of starburst galaxies inside the cluster region.”

Upcoming space missions, such as ESA’s Herschel Space Telescope, will take these infrared observations to the next level, watching how filaments and clusters affect the growth of galaxies in greater detail.

Original Source: NASA/Spitzer News Release

January 28, 2008December 26, 2015 by Fraser Cain

Natural Particle Accelerator Dwarfs the Power of the Large Hadron Collider

Years of work are about to pay off, as Europe’s Large Hadron Collider is almost ready to come online. Soon physicists will be awash in data from the highly energetic particle collisions generated in the facility. But Nature, as usual, already has the upper hand, with a natural particle accelerator capable of pushing particles with 20 times as much energy as the LHC.

ESA’s Integral gamma ray observatory has been watching one of the brightest X-ray regions in the sky, known as the Ophiuchus galaxy cluster. And it’s turned up evidence that the violent region is acting like a natural particle accelerator, pushing electrons to enormous energies.

What kind of environment could create this?

You think the Sun is hot, clocking at a few thousand degrees Kelvin. But the gas in Ophiuchus is more than 100 million degrees Kelvin. Ophiuchus actually contains two galaxies clusters in the process of merging. The violence of this merger sends intense shockwaves rippling through the superheated gas.

The researchers are considering two specific mechanisms for how these X-rays are produced, and are planning follow-up observations to understand it better. In one situation, electrons are caught in the magnetic field threading through the cluster. As they spiral around, they would release the X-ray radiation. In a second scenario, the electrons would actually carry 100,000 times as much energy, and might be colliding with the background microwave radiation in the Universe, left over from the Big Bang.

It’s this X-ray radiation that Integral spotted.

Ophiuchus is able to give particles 20 times as much energy as researcher are hoping to coax out of the Large Hadron Collider.

“Of course the Ophiuchus cluster is somewhat bigger,” says StÃ©phane Paltani, a member of the team. While LHC is 27 km across, the Ophiuchus galaxy cluster is over two million light-years in diameter.”

Original Source: ESA News Release

January 28, 2008December 26, 2015 by Fraser Cain

A Nova Doesn’t Create, It Destroys

Astronomers used to think that brief stellar eruptions called novae generated massive amounts of dust. But new observations of a well known nova system called RS Ophiuchus shows that isn’t the case. The dust was there already, and a nova blast just clears it all away.

The discovery was made using the massive Keck Interferometer, where the two 10-metre (33 feet) Keck telescopes on Hawaii’s Mauna Kea are merged together into a single super-telescope. It’s not like some kind of Japanese anime robot linking together; the telescopes just sit there. All the merging is done behind the scenes, through optics, electronics, and computers.

The Keck Interferometer can null the light coming from a star, revealing its surroundings. This allows the combined instrument to see objects with 10 times more resolving power than a single telescope working alone.

This “nulling mode” is largely used to reveal planet-forming disks of gas and dust surrounding distant stars. With the nuller blocking the starlight, the dimmer disk can be revealed.

In this recent observation, the Keck Interferometer observed a nova in a star surrounded by a dusty disk. The system contains a white dwarf and a red giant. The red giant is shedding its outside layers, while the white dwarf is gobbling it up.

Once a certain amount of matter piles up on the surface of the white dwarf, it explodes in a bright nova. This star has had 5 outburst over the last 100 years, so astronomers knew it would be flaring up again shortly.

The astronomers didn’t see any dust in the inner regions near the star – it was probably vaporized in the explosion. But around 20 times the Earth-sun distance, the researchers did see the dust again.

This flies in the face of what we expected. Astronomers had previously thought that nova explosions actually create dust,” said Richard Barry of Goddard, lead author of the paper on the observations that will appear in the Astrophysical Journal. They were expecting the nova to generate the dust. But instead, the dust was already there, and the nova just illuminated it.

The researchers now think that the dust is created as the star passes through the red giant’s wind, creating a pinwheel pattern around it. The denser regions in this pinwheel are cool enough to stick together to form dust particles. The blast wave from the nova destroys the pinwheel of dust, but it’ll reform again in the next few years.

Ready for another nova blast to blow it all apart again.

Original Source: NASA/JPL News Release